In the game Civ V, vanilla, as a test I tried several 2 vs 1s, allied with an AI against one. (3 civ, random leader, no city-states, map from tiny to big)
On purpose, I did very little to help. (Sometimes, I simply put the difficulty to 7. It should still have been a passive boost to my colleague, and the low number of AI doesn't make it come from increased aggressiveness from the enemy.)
The result: our team lost every time. (25 times) with domination, culture or science victory mostly. the fact is : IA +1 person searching some science was less efficient than one IA alone and we were crushed on the middle term
Is there a handicap 'balancing' the teams?